1. Field of the Invention
This invention relates to piezoelectric acoustic transducers for use in acoustic pulse-echo ranging systems.
2. Review of the Art
In order to obtain satisfactory results when using such a transducer, it is desirable that the ringing characteristics of the transducer be carefully controlled. By "ringing" is meant the continued resonance of the transducer following the end of its transmission of a pulse of acoustic energy. In general, whilst it is desirable that such ringing should decay as rapidly as possible so that it does not mask wanted return echoes, excessive damping of the transducer to reduce ringing is to be avoided since it greatly reduces transducer efficiency in both transmitting and receiving modes. Not only is it difficult to obtain consistent ringing performance as between different transducers of the same nominal characteristics, but ringing performance can be substantially effected by environmental factors such as temperature and the physical mounting of the transducer.
More specifically, it has proved difficult to mount transducers without significant acoustic energy from the transducer being transmitted to the supporting structure, and in some instances this structure may act as a sounding board which can greatly aggravate the ringing problem in a manner which is difficult to predict or control. Efforts have therefore been made to design mountings for such transducers which minimize the transmission of acoustic energy by one means or another but the mounting of transducers to provide consistent ringing performance remains an art rather than a science.